This i see daily, [Linked Image] green is usually a trade standard for a 30 A fuse, and as most older wiring is 14 or 12 gauge, one look says it all.

the circuitry supported the dwelling originally, but it did not get upgraded as our electrical addiction grew.

someone simply inserted a higher amp fuse, so now the fuse is
[Linked Image]NO LONGER THE WEAKEST LINK [Linked Image]
in the circuit, which was it's primary job.....

onto the NEC...

Quote

from 240.4 (D)....

(D) Small Conductors. Unless specifically permitted in 240.4(E) through (G), the overcurrent protection shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10 AWG copper; or 15 amperes for 12 AWG and 25 amperes for 10 AWG aluminum and copper-clad aluminum after any correction factors for ambient temperature and number of conductors have been applied.